Electrical apparatus



' Oct. 29, 1935. c, McNElL ELECTRICAL APPARATUS Filed Sept. 15, 1930.

m mn W Km 0 M 6n mad w m 7 m c Patented Oct. 29, 1935 UNITED STATESPATENT OFFICE ELECTRICAL APPARATUS Application September 13, 1930,Serial No. 481,755

13 Claims.

The present invention relates to electrical circuit arrangements forcharging systems, and more particularly to a novel arrangement forcharging circuits wherein a reverse current relay or cutout is employedto open a generator circuit when the voltage of the generator becomesless than that of the battery to prevent discharging of the latter.

It has been found in practice that the reverse current relay or cut-outemployed in systems 01 the above type does not always function in theintended manner, due to the fact that the apparatus is occasionallysubjected to a severe jolt, as for example when employed on an aircraftand at the instant of landing, which causes the armature of the reversecurrent relay to close accidentally, thereby allowing a heavy current topass through the series coil of the relay, resulting in the armaturebeing held closed by the flux produced by said current which flows fromthe battery through said series coil after the generator voltage hasfallen below that of the battery due to the generator speed decreasingunder these conditions.

Therefore, one of the objects 01 the present invention is to providenovel circuit means whereby the above and other diiiiculties areovercome and the reverse current relay is made to function in theintended manner.

Another object is to provide in a charging circuit, a novel circuitarrangement including a reverse current relay or cut-out and amulti-coil electro-magnet, the various coils of which are so arrangedand combined as to insure proper operation of the circuit regardless ofthe electrical condition of the relay.

A further object is to provide a novel circuit including a reversecurrent relay or cut-out and a novel switch embodying an electro-magnetprovided with a plurality of coils whereby the contacts of the relay. ifclosed accidentally, are prevented from remaining closed.

. Another object is to provide a novel charging circuit including incombination, a reverse current relay and a novel switch whereby saidcircuit is automatically opened when the generator voltage falls belowthe battery voltage to prevent battery current from flowing through therelay if the latter be closed accidentally, thereby preventing saidrelay from remaining closed.

Another object is to provide in a charging circuit, novel arrangementwhereby said circuit is automatically opened when the generator voltagedrops below that of the battery being charged, and caused to remainopen.

(CI. TIL-314) A further object is to provide in a charging circuit formotor vehicles, a novel arrangement whereby said circuit must initiallybe closed manually and thereafter opened automatically when thegenerator voltage falls below the battery 5 voltage, and caused toremain open until manually re-closed.

A still further object is to provide in a charging circuit for motorvehicles, a novel arrangement whereby said circuit is openedautomaticali0 1y when the generator voltage falls below the batteryvoltage and thereafter prevented from accidental closure and wherebysaid circuit may be manually closed and opened at the will oi theoperator oi the vehicle. iii

Still another object is to provide a novel and improved automatic safetyswitch adapted for use in charging circuits on motor vehicles such asairplanes and automobiles.

The above and other objects and advantages of 20 the invention willappear more fully hereinafter from consideration of the detaileddescription which follows, together with the accompanying drawing,wherein is illustrated one embodiment of the invention. It is to beexpressly un- 25 derstood, however, that the drawing is for the purposeof description only, and is not designed as a definition of the limitsoi the invention, reference being bad for this purpose to the appendedclaims. 30

In the drawing, wherein like reference characters refer to like partsthroughout the several views,

Fig. 1 is a schematic circuit arrangement which includes, among otherelements, switch 5 mechanism embodying the present invention;

Fig. 2 is a front elevation, partially in section, with parts brokenaway, of one form of switch adapted to be employed in accordance withthe invention; and

Fig. 3 is a partially sectional side view tl'iereoi taken on line 3-3 ofFig. 2.

Referring now to Fig. 1, the embodiment of the invention illustratedtherein is employed in a circuit including a direct-current generator 45provided with the usual voltage regulator and a reverse current relay orcut-out adapted to function in the usual manner in charging a storagebattery, such as is generally employed for providing electrical energyfor starting and lighting of a motor vehicle and for operating otherauxiliary apparatus as is generally provided on such vehicles.

In the form shown, the voltage regulator comprises the usual solenold 4provided with a shunt Iii or voltage winding I in series with aprotective resistance 8, said solenoid being adapted upon energizationof the coil 5 to open contacts 1 and 3,which are normally held closed bya spring 9, thereby placing a resistance III in series with the shuntfleld winding ll of the generator l2.

The tension of the spring 9 is adjusted so that, upon the rise of thevoltage from the generator l2 above a predetermined value, the contacts1 and 3 are opened, thereby causing resistance III to decrease thecurrent flow in fleld winding H, thus reducing the speed of thegenerator and decreasing the voltage thereof.

The reverse current relay or cut-out, which is through from thegenerator their flux is cumulative, thereby holding the contacts l1 andI8 closed against the tension of spring l9, but when ing held closed bytheflux produced in said coil.

the current flows from the battery to the generator due to the voltageof the latter being greater than that of the generator, themagneto-motive forces of the coils oppose each other, thereby causingthe contacts l1 and It to be opened by the spring I 9.- As -isunderstood in the art, coil l5 functions to initially close the contactsI! and i8, whereby current is then caused to flow through coil 14, thusaiding the coil ii in keeping said contacts closed.

As pointed out hereinbefore, it has been found in practice that areverse current relay or cutoutdoes not always function in the intendedmanner due to the fact that the contacts I! and II are occasionallyclosed accidentally when the motor vehicle on which the device ismounted is subjected to a severe jolt, thereby causing a heavy currentto flow from the battery through the coil l4 and resulting in thecontacts l1 and I. be-

Means are therefore provided whereby the battery circuit isautomatically opened and held opened'when the generator voltage fallsbelow that of the battery, thus preventing any battery current fromflowing through the series coil of the reverse current relay if thelatter be closed accidentally; which would tend to hold it closed andcause discharging of the battery and possibly a burning out of thegenerator due to said battery current flowing therethrough.

In the form shown, said means comprises a electro-magnet or solenoid 20provided with a shunt winding 2| and a series winding 22 whichcorrespond to windings l3 and I4, respectively, of the reverse currentrelay and are adapted to hold contacts 23 and 24 closed when the battery25 is being charged by the generator and are wound in a manner similarto that of coils l5 and I4, so that when the generator voltage drops,current from the battery 25 flowing through said coils is in oppositedirections, thereby causing spring 26 to open the contacts 23 and 24 atthe same time that contacts I I and II are opened by spring I! and theaction of coils l4 and I5. This device differs from a reverse currentrelay in that the tension of spring 241s of such a value asto preventthe contacts 23 and 24 from closing only by attraction of the armaturedue to generator current passing through 1011 II. and

the contacts 23 and 24 must initially be closed manually against thetension of said spring, whereupon generator current flows through coil22 andthe flux produced therein is in the same direction as that of coil2|, thereby causing the solenoid 20 to hold said contacts closed. I

It will therefore be apparent that before the system can operate,contacts 23 and 24 must be closed manually, but when once closed theywill be held closed by the combined action of coils 2| and 22. Due tothe tension of the spring 26, accidental closure of the contacts cannotoccur after they are opened, as may happen in the case of the reversecurrent relay, in which the tension of the spring I9 is much lower andinsuflicient to prevent the contacts l1 and I8 coming together when thevehicle on which the relay is carried is subjected to a Jolt or jar.Spring l9 must, of necessity, be made light in order that the relayfunction properly, because if the tension of said spring were increasedthe energization of the coil I5 would be insufficient to close thecontacts when necessary. Contacts 23 and 24 of the novel switch arearranged so that they may also be opened manually as well asautomatically, if desired, at the will of the operator of the motorvehicle upon which said switch is mounted, which will be pointed outmore particularly in connection with Figs. 2 and 3.

The device is provided with three terminals 21, 28, and 29, the firsttwo of which are adapted to be connected'to the plus or positive side ofthe generator and the positive side of the battery, respectively, andthe third to the negative side of the generator and the negative side ofthe battery.

Referring now to Figs. 2 and 3, which show one form of mechanicalembodiment of the invention, the device illustrated therein comprises arectangular frame 30 provided with integral flanges 3| and 32 at one endthereof for securing the device to the instrument panel of an aircraftor the dashboard of an automobile. Threaded apertures 33 are formed inthe frame for receiving screws 34 by means of which a pair ofcoverplates 35 and 36 are secured to the frame. The core 20, on whichare wound the coils 2| and 22, is carried by a rectangular member orshelf 3'! which is pressed into the frame either from the front or therear thereof, and also carries an adjusting mechanism to be describedhereinafter. Terminals 21, 28, and 29 extend from and pass through theother end of the frame and are insulated'therefrom by means of bushings38, 33,

and 40 of some suitable insulating material, such as fibre, bakelite, orthe like. The inner ends of the terminals are provided with bindingposts 4I 42, and 43, respectively, for connecting the coils 2i and 22and contact 24 thereto.

The movable contact 23 is carried by an ar mature 44 positioned parallelwith and longitudinally of the coils and is pivoted by means of a pin 45passing therethrough and supported in the shelf 31. Coil 22 may beconnected to armature 44 in any suitable manner, as by soldering theendthereof to said armature as indicated at 44a. Fixed contact 24 iscarried by a bracket 46 of some suitable conducting material, such asbrass or copper, which is rigidly secured to the terminal 23 by means ofthe screw of the binding post 42. When the coils 2| and 22 areenergized, the magnetic path of the flux produced thereby is from thecore 20 through the shelf 31, the armature 44, and back to the core 20.It will be apparent that upon energization of the coils the armature uwill be attracted to the left by the core 20, thereby closing thecontacts 23 and 24 against the tension of the spring 28, which issecured to one end of said armature.

--ture through which the member 41 passes and by means of which saidmember is adapted to 4 be moved either to the right to decrease thetension on the spring 26, or to the left to increase the tension byrotating the head 4| of the mem ber 41. Guide member I0 is secured tothe shelf 31 by suitable means such as a screw II and serves to guidethe end piece 48 and also to support the latter. In order to prevent anychange in the adjustment, a ratchet wheel 52 is provided which iscarried by the threaded member 41 concentrically therewith and isadapted to be engaged by a pawl 62, the latter being secured to thebracket ill by means of screw ii. The teeth on the ratchet wheel arearranged to provide rotation thereof in either direction against thepressure of the pawl 52 but prevented from rotation by the latter untilsome external force is applied thereto, as by means of rotation of thehead 40 of the threaded member 41. It will be apparent from thisconstruction that once an adjustment is made it will be maintained untilaltered by manipulation .of the threaded member 41.

Means are also providedfor manually closing and opening the contacts 22and 24 at the will of the operator, and in the form shown comprise aknob 64 secured to or made integral with a rod which passes through anaperture formed in that portion of the frame 20 which is adapted tolie'on the face of the instrument panel. The rod is provided with a setof collars or discs N. 51, and 52 spaced apart from each othertherealong. A leaf spring I8 is secured at its one end to the frame 30,as by means of a rivet 40, and has its free end interposed between thecollars I4 and 81 whereby, upon inward and outward movement of the knob54. the latter is returned to its normal position, as indicated in Fig.2. The collar 51 is positioned on the rod I! so that when the contacts2| and 24 are closed it bears against an angular projection Bl securedto the end of the armature 44 opposite from that which carries the fixedcontact 23, whereby upon an inward push of knob 54 the contacts 22--24may be opened. The collar 5| is positioned on the 'end of the rod 55 sothat upon an outward movement of the knob I4 it engages the projectionII and causes the armature 44 to move on its pivot pin 45 to close thecontacts 21 and 24.

The operation of the device is as follows: When the engine of the motorvehicle on which the device is mounted is started the generator I2 isrotated thereby and current from the latter flows through the shunt coilll, causing energization of the reverse current relay to close thecontacts I! and II. No current flows through series coil i4 untilcontacts 22 and 24 are closed manually when it is desired to charge thebattery 25. To close said contacts, knob 54 is pulled outward, causingcurrent from the generator to pass through coils 2i and 22, therebyproducing a flux which tends to hold said contacts in closed position.Contacts l1 and it, being closed,-cause current to flow through coil i4,thereby increaswill flow through-coils 2| and 22 and coils l4 and ii inopposite directions, thereby substantially decreasing the flux thereof,causing springs 20 and I! to automatically open the contacts 22-24 andl4'll. However, after the contacts 23-24 are open they are held open bythe spring 28, and cannot be closed again until the knob 54 is pulledoutward to cause current from the generator to traverse the coils in thesame direction and thereby hold the contacts closed.

If the operator desires to discontinue charging the battery at any time,he simply has to push the knob 54 inward to break the contacts 28 and24, which are thereafter held open by means of spring 20, aspointed outabove. When the contacts 28 and 24 are opened, either manually orautomatically, no battery current can flow through the series coil l4 ofthe reverse current relay should the contacts i1 and ll .be closedaccidentally by a sudden jolt or Jar imparted to the motor vehicle as,for example, when landing 1 an airplane. v

It will be seen from the foregoing description that there is provided anovel charging circuit or'system adapted for use particularly inaircraft, which are frequently subjected to jolts and jars, wherebyaccidental closing of thcreverse current relay is prevented, thuspreventing discharging of the battery through the generator.

The mechanical embodiment of the switch which is also novel and simplein structure, thereby 4 facilitating the assembly and manufacturethereof and reducing the cost of manufacture, the subject of adivisional application Serial No. 558,373, filed August 20, 1931.

While only one embodiment oi the invention is 4 shown and described,various other changes in form, arrangement, and construction of parts,which will now appear to those skilled in the art, may be made withoutdeparting from the scope of the invention, and reference is therefore tobe had to the appended claims for a definition or the limits of theinvention.

What is claimed is:

1. In a system oi the class embodying a generator, a battery adapted tobe connected therewith, and a reverse current relay between thegenerator and battery comprising a movable switch member and series andshunt coils, the combination with saidrelay of means for preventing theswitch member being held inclosed c position by the passage of heavybattery current through the series 0011 and including a switch requiredto be actuated manually for connecting the battery to the generator butresponsive to a flow of battery current for automatically discon- 5necting the battery from the generator.

2. In a system of the type which embodies a generator, a battery adaptedto be connected therewith, and a reverse current relay betweenthegenerator and battery comprising an arma- 7 I ture and series andshunt coils, the combination with said relay of automatic means forpreventing the armature being held in closed position by the passage ofheavy battery current through the series coil and including a switchrequired to be actuated manually for connecting the bat-. tery to thegenerator but responsive to a flow of battery current for automaticallydisconnecting the battery from the generator.

3. In a charging circuit oi the type embodying a generator, a batteryadapted to be connected therewith, and a reverse current relay betweenthe generator and battery comprising a pair of contacts and series-andshunt coils, the combina-' tion with said relay of an electro-magneticswitch provided with a plurality of coils, and a pair of contactsrequired to be closed manually and adapted to be held closed by currentpassing from the generator to the battery, said coils being so arrangedthat when the generator voltage becomes less than the battery voltagesaid switch is automatically opened simultaneously with the reversecurrent relay, thereby preventing accidental closing of said relay.

4. In a charging circuit 0! the class including a generator, a batteryadapted to be connected therewith, and a reverse current relay betweenthe generator and battery comprising. a pair of contacts and series andshunt coils, the combination with said relay of a switch. required to beactuated manually to connect the battery to the generator and providedwith series and shunt coils and a pair of contacts in series with saidseries coil, means for manually closing said contacts whereby current iscaused to flow from the generator to the battery through the series coilor the switch and the series coil of the relay for respectively holdingthe relaycontacts and the switch contacts closed, said relay and switchcoils beingso arranged that both pairs of contacts will open when thegenerator voltage drops below. the battery voltage and so that the relaycontacts cannot close the generator battery circuit until the switchcontacts are manually re-closed.

5. In a charging circuit of the class embodying a generator, a batteryadaptedto be connected Y the relay is eliminated, and means for manuallyclosing and opening said switch independently of the voltages asdesired, said relay being ineffective until the switch is closed.

6. In a charging circuit of the class including a generator, a batteryadapted toibe connected therewith, and a reverse current relay betweenthe generator and the battery comprising a pair 01' contacts and seriesand shunt coils, the combination with said relay of a switch required tobe actuated manually to connect the battery to the generator and alsoincluding series and shunt coils and a pair of contacts adapted to beclosed manually and opened automatically when the generator voltagefalls below the battery voltage, said relay, and switch coils being soarranged said control means comprising a solenoid *havnected therewith,and a reverse current relay between said generator and battery,thecombination with said relay 0! a switch required to be manuallyactuated to connect the battery to the generator and including a pairoicontacts, 5

means for manually opening and closing said contacts, a plurality ofcoils arranged so that when current flows from the generator to thebattery said coils are energized in the same sense to hold saidcontacts'closed, and when current 10 flows from the battery to thegenerator upon a decrease oi the generator voltage below that of thebattery voltage said contacts are automatically opened, and means formaintaining said contacts in open position until they are re-closed 15tor, a reverse current cut-out between the generator and battery andhaving series and shunt coils, and a switch required to be actuatedmanually to close the generator-battery circuit but adapted to beoperated automatically when cur- 2 rentflbws from the battery to thegenerator for opening said circuit and 'for disconnecting the shunt coilfrom the battery.

9. In a battery charging system, a generator, a battery adapted to beconnected to said generator;

' a reverse current cut-out having series and shunt .coils connected tothe generator-battery circuit, a switch required to be actuated manuallyfor closing the generator-battery circuit and having T battery adaptedto be connected to said gene ra- 20,

series and shunt coils which are connected to be 35 energized in likemanner when the switch is closed I manually and current is flowingfromthe generator to the battery but adapted. to be energized in oppositesenses when current flows from the battery to the generator for openingthe generator-battery circuit' and for disconnecting the shunt coils ofthe cut-out and 01' the switch from I the battery.

10. In combination with a generator and a battery, each connected acrossa main circuit adapted to feed an external load, a reverse-currentcontrolled switch located in said main circuit, a manually closableswitch in series withsald firstnamedswitch, and control means responsiveto an opening of said first-named switch to operate upon saidsecondswitch for maintaining said circuit open as long as the generatorvoltage remains below the predetermined value at which said first-namedswitch is opened, said control means comprising a solenoid havingopposing windings,-one of which tends to close said switch and the otherof which tends to render the first winding ineffective.

11. Incombination with a generator and a battery, each connected acrossa main circuit adapted to feed an external load, a reverse-cirrrentcontrolled switchlocated in said main circuit, a manually closableswitch in series with said'first-named switch, and control meansresponsive to an opening of said first-named switch to operate upon saidsecond switch for maintaining said circuit open as long as the generatorvoltage remains below the predetermined value at which said first-namedswitch is opened,

ing opposing windings, one of which tends to close said switch and theother of which tends to render the first winding'ineflective, saidsecond winding being in shunt with said generator and said battery.

12. In combination with a generator and a battery, each connected acrossa main circuit adapted to feed an external load, a reverse-currentcontrolled switch located in said main circuit, a closable switch inseries with said firstnamed switch, and control means responsive to anopening of'said first-named switch to operate winding ineffective, andresilient means for re-' opening said second switch when the potentialdifference across said second winding is sufiicient to neutralize themagneto-motive force of said first-named winding.

13. In combination with a generator and a battery, each connected acrossa main circuit adapted to feed an external load, a reverse-currentcontrolled switch located in said main circuit, a closable switch inseries with said first-named switch, control means responsive to anopening of said first-named switch to operate upon said second switchfor maintaining said circuit open as long as the generator voltageremains below the predetermined value at which said firstnamed switch isopened, said control means com- 3 prising a solenoid having opposingwindings, one of which tends to close said switch and the other of whichtends to render the first winding inefiective, said second winding beingin shunt with said generator and said battery, and resilient means forre-opening said second switch when the po-- tential difference acrosssaid second winding is suflicient to neutralize the magneto-motive forceof said first-named winding.

CHARLES I. McNElL.

